Display panel and manufacturing method of the same

ABSTRACT

Provided are a display panel which can detect a touch position derived from a user&#39;s touch and can prevent erroneous touch position data from being generated even when an erroneous connection to a position sensing line is present due a processing deviation or a cell gap deviation, and a manufacturing method of the same. The display panel includes a first substrate, a first sensor pad that is formed on the first substrate, a second sensor pad that is spaced apart from the first sensor pad, a second substrate that is disposed to face the first substrate, a first sensor spacer that is formed on the second substrate to overlap the first sensor pad and protrudes toward the first substrate, a second sensor spacer that is formed on the second substrate to overlap the second sensor pad and protrudes toward the first substrate, and a sensor electrode that is formed on the first sensor spacer and the second sensor spacer to overlap the first sensor pad and the second sensor pad, wherein the second sensor spacer protrudes toward the first substrate more than the first sensor spacer does.

CROSS-REFERENCE TO RELATED APPLICATION

This application is a Divisional Application of U.S. patent applicationNo. 12/614,377 filed on Nov. 6, 2009, which claims priority from KoreanPatent Application No. 10-2008-0133669 filed on Dec. 24, 2008 in theKorean Intellectual Property Office, the disclosures of which areincorporated herein by reference.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a display panel and a manufacturingmethod of the same, and more particularly, to a display panel which candetect a touch position derived from a user's touch and can preventerroneous touch position data from being generated even when physicaldefects arising from a processing deviation or a cell gap deviation arepresent, and a manufacturing method of the display panel.

2. Description of the Related Art

A touch panel is an input means installed on an uppermost portion of adisplay device, such as a liquid crystal display (LCD), a field emissiondisplay (FED), a plasma display panel (PDP) or an electroluminescencedisplay (ELD), to detect contact with a finger or a touching object,such as a stylus, so that the user may select one of a number of areasin which information is displayed on the screen of the display device.

Touch panels fall into two categories according to the operationalprinciple used, namely, capacitive-type touch panels and resistive-typetouch panels. In the capacitive-type touch panel, a transparentconductive film or a transparent conductive glass plate is repeatedlycharged and discharged, as a small amount of charge accumulates betweena pen-type input device, e.g., a stylus, and the transparent conductivefilm, and the amount of charge is detected to obtain coordinate valuesof the touched point. In the resistive-type touch panel, a voltage isapplied between two conductive films facing each other, a user presses ascreen to make the two conductive films contact each other, and a changethat occurs in the voltage or current at a contacted point between thetwo conductive films is detected to read coordinate values of thecontacted point.

Since the capacitive-type touch panel is disadvantageous in that it isnecessary to supply electricity to a stylus for the capacitive-typetouch panel, a resistive-type touch panel based on an analogue inputmethod has recently been put into wide use. Here, the resistive-typetouch panel may be integrated with a liquid crystal display panel,thereby preventing degradation in the luminance of the liquid crystaldisplay panel.

The touch-panel-integrated liquid crystal display panel includes a firstsensor line and a second sensor line formed on a TFT substrate inhorizontal and vertical directions to detect a first coordinate for aposition of an input point and a second coordinate for a position of theinput point. In addition, the touch-panel-integrated liquid crystaldisplay panel includes sensor pads formed on the TFT substrate and asensor spacer and a sensor electrode formed on a color filter substrateto make the first sensor line come in contact with the second sensorline in response to pressure applied by a finger or stylus.

A height difference between sensor spacers formed on either the TFTsubstrate or on the color filter substrate may occur because ofvariations in dimensions arising from manufacturing processingvariations. A deviation in the thickness of a cell gap, the gap betweenthe TFT substrate and the color filter substrate of the display panel,may also occur. For these reasons, a contact between the sensorelectrode and the sensor pad may undesirably occur even before a usertouches the display panel, thus giving a false indication of a locationof pressure application.

SUMMARY OF THE INVENTION

The present invention provides a display panel which can determine thecoordinates of a touch position derived from a user's touch and canprevent false touch information from being generated even when amanufacturing processing deviation or a cell gap deviation is present inthe display panel.

The present invention also provides a manufacturing method of a displaypanel which can determine a touch position derived from a user's touchand can prevent false touch position information from being generatedeven with a processing deviation or a cell gap deviation.

These and other objects of the present invention will be described in orbe apparent from the following description of the preferred embodiments.

According to an aspect of the present invention, there is provided adisplay panel including a first substrate, a first sensor pad that isformed on the first substrate, a second sensor pad that is spaced apartfrom the first sensor pad, a second substrate that is disposed to facethe first substrate, a first sensor spacer that is formed on the secondsubstrate to overlap the first sensor pad and protrudes toward the firstsubstrate, a second sensor spacer that is formed on the second substrateto overlap the second sensor pad and protrudes toward the firstsubstrate, and a sensor electrode that is formed on the first sensorspacer and the second sensor spacer to overlap the first sensor pad andthe second sensor pad, wherein the second sensor spacer protrudes towardthe first substrate farther than the first sensor spacer.

According to another aspect of the present invention, there is provideda display panel including a first substrate, a second substrate that isdisposed to face the first substrate, a common electrode that is formedon the second substrate, a first sensor spacer that is formed on thefirst substrate and protrudes toward the second substrate, a secondsensor spacer that is formed on the first substrate and protrudes towardthe second substrate, a first sensor pad that is formed on the firstsensor spacer, a second sensor pad that is formed on the second sensorspacer and is spaced apart from the first sensor pad, and a sensorelectrode that is formed on the second substrate to overlap the firstsensor pad and the second sensor pad, wherein the second sensor spacerprotrudes toward the second substrate farther than the first sensorspacer.

According to still another aspect of the present invention, there isprovided a manufacturing method of a display panel, the method includingforming a first sensor pad and a second sensor pad that are spaced apartfrom each other on a first substrate, forming a first sensor spacer anda second sensor spacer on a second substrate to overlap the first sensorpad and the second sensor pad, respectively, and to protrude toward thefirst substrate, the second sensor spacer protruding toward the firstsubstrate farther than the first sensor spacer, forming a sensorelectrode on the first sensor spacer and the second sensor spacer tooverlap the first sensor pad and the second sensor pad, and disposingthe second substrate to face the first substrate.

BRIEF DESCRIPTION OF THE DRAWINGS

The above and other features and advantages of the present inventionwill become more apparent in view of the following detailed descriptionof preferred embodiments thereof, taken with reference to the attacheddrawings in which:

FIG. 1 is a layout view of a representative portion of a lower panel ofa display panel according to a first embodiment of the presentinvention;

FIG. 2 is a cross-sectional view of the representative portion of thedisplay panel taken along the line II-II′ of FIG. 1 and including anupper panel in addition to the lower panel of FIG. 1;

FIGS. 3A through 3C are cross-sectional views schematically showing theoperating process of the display panel shown in FIG. 1;

FIGS. 4A and 4B are cross-sectional views schematically showing theoperating process of a display panel having one of two sensor padscontacting a sensor electrode;

FIGS. 5A through 5D are cross-sectional views showing the manufacturingprocess of an upper panel of the display panel shown in FIG. 1;

FIG. 6 is a cross-sectional view of a display panel according to asecond embodiment of the present invention; and

FIG. 7 is a cross-sectional view of a display panel according to a thirdembodiment of the present invention.

DETAILED DESCRIPTION OF THE INVENTION

Advantages and features of the present invention and methods ofaccomplishing the same may be understood more readily by reference tothe following detailed description of preferred embodiments and theaccompanying drawings. The present invention may, however, be embodiedin many different forms and should not be construed as being limited tothe embodiments set forth herein. Rather, these embodiments are providedso that this disclosure will be thorough and complete and will fullyconvey the concept of the invention to those skilled in the art, and thepresent invention will only be defined by the appended claims.Accordingly, in some specific embodiments, well known processing steps,devices or methods will not be described in detail in order to avoidobscuring the invention. Like numbers refer to like elements throughout.

Spatially relative terms, such as “below”, “beneath”, “lower”, “above”,“upper”, and the like, may be used herein for ease of description todescribe one element or feature's relationship to another element(s) orfeature(s) as illustrated in the figures. It will be understood that thespatially relative terms are intended to encompass differentorientations of the device in use or operation in addition to theorientation depicted in the figures. For example, if the device in thefigures is turned over, elements described as “below” or “beneath” otherelements or features would then be oriented “above” the other elementsor features. Thus, the exemplary term “below” can encompass both anorientation of above and below.

The terminology used herein is for the purpose of describing particularembodiments only and is not intended to be limiting of the invention. Asused herein, the singular forms “a,” “an” and “the” are intended toinclude the plural forms as well, unless the context clearly indicatesotherwise. It will be further understood that the terms “comprises”and/or “comprising,” when used in this specification, specify thepresence of stated features, integers, steps, operations, elements,and/or components, but do not preclude the presence or addition of oneor more other features, integers, steps, operations, elements,components, and/or groups thereof.

Hereinafter, a display panel according to a first exemplary embodimentof the present invention will be described in detail with reference toFIGS. 1 through 3.

A display panel according to a first embodiment of the present inventionwill first be described with reference to FIGS. 1 and 2. FIG. 1 is alayout view of one pixel of a display panel according to a firstembodiment of the present invention and FIG. 2 is a cross-sectional viewof the display panel taken along the line II-II′ of FIG. 1. FIG. 1includes a lower panel only whereas FIG. 2 includes the lower panel andan upper panel. The pixel shown in FIG. 1 is one of an array of pixelsarranged in rows and columns. The coordinates of a pixel are X and Y,where X is the number of the row and Y is the number of the column inwhich the pixel is located.

The display panel according to the first embodiment of the presentembodiment includes a lower panel 100 and an upper panel 200, facingeach other, and a liquid crystal layer 300 interposed between the lowerand upper panels 100 and 200.

The lower panel 100 includes a first substrate 110 upon which aredisposed a gate line 121, a first sensor line 123, a data line 162, asecond sensor line 166, a thin film transistor (“TFT”), a pixelelectrode 181, a first sensor pad 182, and a second sensor pad 183.

The gate line 121 extends in a first direction to transmit a gate signalto the TFT. In an exemplary embodiment, the first direction may be atransverse direction, that is to say the Y direction as shown in FIG. 1.The gate line 121 may be formed as a single layer or multiple layersmade of molybdenum (Mo), niobium (Nb), copper (Cu), aluminum (Al),chromium (Cr), silver (Ag), tungsten (W), titanium (Ti), or alloysthereof. The TFT includes a gate electrode 122 that is formed such thatthe gate electrode 122 is a branch extended from the gate line 121.

The first sensor line 123 extends in the first direction and is parallelwith the gate line 121. The first sensor line 123 is formed in the samelayer using the same material as that used for the gate line 121. A gateinsulating film 130 is coated on the gate line 121 and the first sensorline 123.

A semiconductor layer 140 is formed of hydrogenated amorphous silicon orpolycrystalline silicon on the gate insulating film 130. Ohmic contactlayers 155 and 156 are formed of a silicide or of a material heavilydoped with n-type impurities, such as n+ hydrogenated amorphous silicon.The ohmic contact layers 155 and 156 are disposed as a pair on thesemiconductor layer 140, with a gap separating the ohmic contact layer155 from the ohmic contact layer 156.

A source electrode 163 extending from the data line 162, and a drainelectrode 164 corresponding to the source electrode are formed on theohmic contact layers 155 and 156, respectively, and on the gateinsulating film 130.

The data line 162 is formed on the first substrate 110 and extends in asecond direction to transmit a data signal to each pixel. In anexemplary embodiment, the second direction may be a longitudinaldirection, that is to say the X direction as shown in FIG. 1. That is tosay, the data line 162 and the gate line 121 may be formed to cross eachother. The data line 162 may be formed as a single layer or multiplelayers made of molybdenum (Mo), niobium (Nb), copper (Cu), aluminum(Al), chromium (Cr), silver (Ag), tungsten (W), titanium (Ti), or alloysthereof.

The second sensor line 166 is formed parallel with the data line 162.The second sensor line 166 is formed in the same layer using the samematerial as that used for the data line 162. The source electrode 163,as stated above, is an extension of the data line 162 extending towardthe drain electrode 164. The drain electrode 164 transmits a data signalto a pixel electrode 181.

The gate electrode 122, the source electrode 163 and the drain electrode164 constitute three terminals of a thin film transistor (TFT). The TFTtransmits the data signal input to the source electrode 163 to the pixelelectrode 181 via the drain electrode 164 in response to a gate signal.

The TFT includes the semiconductor layer 140 overlapping the gateelectrode 122 with the gate insulating film 130 disposed therebetween toenable the formation of a channel in the semiconductor layer 140 betweenthe source electrode 163 and the drain electrode 164.

A passivation layer 170 may include, for example, an inorganicinsulating material such as silicon nitride (SiN_(x)) or silicon oxide(SiO_(x)), or an organic insulating material such as acrylic orpolyimide benzoclylobutene (BCB). Here, the passivation layer 170 may beformed as a single layer or multiple layers made of an inorganicmaterial or an organic material. The passivation layer 170 is formed tocover the TFT and the gate insulating film 130, thereby insulating theTFT from the pixel electrode 181.

The passivation layer 170 includes first through third contact holes175, 176 and 177 exposing the drain electrode 164, a first sensor wiringextension 124 of the first sensor line 123 and a second sensor wiringextension 167 of the second sensor line 166, respectively. Here, thefirst through third contact holes 175, 176 and 177 are formed by etchingportions of the passivation layer 170 exposed by a mask.

The pixel electrode 181 is formed on the passivation layer 170. Thepixel electrode 181 is connected to the drain electrode 164 of the TFTthrough the first contact hole 175. The pixel electrode 181 is formed ofa transparent conductor material such as indium tin oxide (ITO) orindium zinc oxide (IZO), or a reflective conductor material such asaluminum.

The first sensor pad 182 is separated by a gap from a sensor electrode252 (to be described later) and, in response to a pressure applied tothe display panel by a finger or stylus comes into contact with thesensor electrode 252 and transmits a signal for recognizing an X-axiscoordinate value to or from the first sensor wiring 123. The firstsensor pad 182 is connected through the second contact hole 176 to afirst sensor wiring extension 124 that extends from the first sensorline 123.

The second sensor pad 183 is separated by a gap from the sensorelectrode 252 and, in response to a pressure applied to the displaypanel by a finger or stylus, transmits a signal for recognizing a Y-axiscoordinate value to or from the second sensor line 166. The secondsensor pad 183 is connected, through the third contact hole 177, to asecond sensor wiring extension 167 that extends from the second sensorline 166.

The first sensor pad 182 and the second sensor pad 183 are formed tooverlap sensor spacers 241 and 242 (to be described later) and thesensor electrode 252. The first sensor pad 182 and the second sensor pad183 may be formed by using the same material as that used for the pixelelectrode 181 and by using the same process as that used for the pixelelectrode 181.

The upper panel 200 includes a second substrate 210, upon which aredisposed a black matrix 220 for blocking light leakage, a color filter230 for displaying colors, and a common electrode 251 for applying acommon voltage to the liquid crystal layer 300.

The second substrate 210 may be formed of a transparent insulatingmaterial, for example plastic or glass, through which light can pass andwhich is capable of forming a smoothly curved surface in response topressure applied to the top surface of the second substrate 210.

The black matrix 220 prevents light from being emitted through a regionwhere liquid crystal is not controllable. It is formed to overlap theTFT, the gate line 121, the data line 162, the first sensor line 123 andthe second sensor line 166, which are provided in the lower panel 100.The black matrix 220 may be formed of an opaque organic material or anopaque metal.

The color filter 230 transmits one of the primary colors red, green, andblue. The color filter 230 absorbs or transmits light of a specificwavelength, for example, through red, green, and blue pigments, therebydisplaying red, green, and blue colors. Various colors are displayed byadditive mixture of the transmitted red, green, and blue colors.

The common electrode 251 is formed over the color filter 230 and theblack matrix 220. An overcoat layer (not shown) may be formed over thecolor filter 230 and the black matrix 220 to achieve good step coverage.The common electrode 251 may be formed on the overcoat layer. Here, thecommon electrode 251 may be a layer of a transparent conductive materialsuch as indium tin oxide (ITO) or indium zinc oxide (IZO). An electricfield is applied through the liquid crystal layer 300 by the applicationof a voltage that is the difference between the common voltage suppliedfrom a common voltage generator to the common electrode 251 and a datavoltage applied to the pixel electrode 181.

The first sensor spacer 241 and the second sensor spacer 242 may beformed on the black matrix 220. In other words, the first sensor spacer241 and the second sensor spacer 242 may be formed to overlap the blackmatrix 220 through which light is not transmitted. The sensor electrode252 is formed on the first sensor spacer 241 and the second sensorspacer 242. The first sensor spacer 241 and the second sensor spacer 242may be formed of an organic material. The first sensor spacer 241 andthe second sensor spacer 242 may also be formed by a process that isused simultaneously for both. In the exemplary embodiment illustrated inFIG. 2, the first sensor spacer 241 and the second sensor spacer 242 areformed by using the same material as that used for the color filter 230,which is, however, provided for illustration only. However, inalternative embodiments, the first sensor spacer 241 and the secondsensor spacer 242 may be formed together with or separately from theovercoat layer (not shown) on the black matrix 220.

The first sensor spacer 241 and the second sensor spacer 242 protrudetoward the first substrate 110. The second sensor spacer 242 protrudestoward the first substrate 110 farther than the first sensor spacer 241does. The first sensor spacer 241 and the second sensor spacer 242 maybe formed adjacent to each other and spaced apart from each other by apredetermined distance.

As described above, the sensor electrode 252 is formed on the firstsensor spacer 241 and the second sensor spacer 242. When a pressure isapplied to a location on the upper panel 200 according to a user'scontact, for example by the application of a finger or a stylus, thesecond substrate 210 becomes curved downward and the first sensor spacer241 and the second sensor spacer 242 are brought into contact with thefirst sensor pad 182 and the second sensor pad 183, respectively, thelocation on the upper panel 200 to which the pressure is applied can bedetermined.

Before an external force is applied to the upper panel 200, the firstsensor pad 182 and the first sensor spacer 241 are spaced apart fromeach other by a predetermined distance. The second sensor pad 183 andthe second sensor spacer 242 are also spaced apart from each other by apredetermined distance. Here, the predetermined distance between thesecond sensor pad 183 and the second sensor spacer 242 may be smallerthan the predetermined distance between the first sensor pad 182 and thefirst sensor spacer 241.

Accordingly, when an external pressure is applied to the upper panel200, the second sensor spacer 242 is first brought into contact with thesecond sensor pad 183. Then, if the pressure exceeds a force supportedby the second sensor spacer 242 is applied to the upper panel 200, thesecond sensor spacer 242 may be compressed and the first sensor spacer241 contacts the first sensor pad 182. If a pressure, e.g., a force of80 gf(gram*force) or greater, is additionally applied in a state inwhich the second sensor spacer 242 contacts the second sensor pad 183,then the first sensor spacer 241 contacts the first sensor pad 182.

A height difference between the second sensor spacer 242 and the firstsensor spacer 241 may be 0.1 μm or greater. If the height differencebetween the second sensor spacer 242 and the first sensor spacer 241 ismaintained to be 0.1 μm or greater, a difference between the distancebetween the first sensor pad 182 and the first sensor spacer 241 and thedistance between the second sensor pad 183 and the second sensor spacer242 can be made to be 0.1 μm or greater.

Also, the sensor electrode 252, formed on the first sensor spacer 241and the second sensor spacer 242, may be formed of the same material asthat used for the common electrode 251 and may be formed by the sameprocess. Further, the sensor electrode 252 may be insulated from thecommon electrode 25 land allowed to float at a floating potential.Alternatively, the sensor electrode 252 may be in electrical contactwith the common electrode 251 or may be an integral part of the commonelectrode 251. The sensor electrode 252 may be formed on the firstsensor spacer 241 and the second sensor spacer 242 in a single islandshape.

In the display panel according to the first embodiment of the presentinvention, when an external pressure is applied to a location on theupper panel 200 according to a user's contact, the first sensor spacer241 and the second sensor spacer 242 contact the first sensor pad 182and the second sensor pad 183, respectively. The sensor electrode 252,which, as stated, is disposed on the first sensor spacer 241 and thesecond sensor spacer 242, connects the first sensor pad 182 to thesecond sensor pad 183. Here, an X-coordinate is obtained when a currentor a voltage is applied through the first sensor line 123 and aY-coordinate is obtained when the applied current or voltage passesthrough the sensor electrode 252 to the second sensor line 166.Alternatively, the current or voltage may be applied to the secondsensor line 166 and detected on the first sensor line 123. The firstsensor spacer 241 and the second sensor spacer 242 are formed to have aheight difference relative to each other. That is to say, one of thefirst sensor spacer 241 and the second sensor spacer 242 is formed to behigher than the other.

Hereinafter, the operating process of the display panel 1 according tothe first embodiment of the present invention will be described withreference to FIGS. 3A through 3C. FIGS. 3A through 3C arecross-sectional views schematically showing the operating process of thedisplay panel shown in FIG. 1.

Referring to FIG. 3A, FIG. 3A illustrates an initial state of thedisplay panel 1, where there is no external pressure applied. In theinitial state of the display panel 1, the lower panel 100 and the upperpanel 200 are parallel with each other. Here, the first sensor spacer241 is separated from the first sensor pad 182 by a predetermineddistance, and the second sensor spacer 242 is separated from the secondsensor pad 183 by a predetermined distance, respectively. The firstsensor pad 182 and the second sensor pad 183 are insulated from eachother.

In the initial state, the distance between the second sensor spacer 242and the second sensor pad 183 is smaller than the distance between thefirst sensor spacer 241 and the first sensor pad 182.

Referring to FIG. 3B, FIG. 3B illustrates a state in which pressure isapplied to the display panel 1, specifically to a top surface of theupper panel 200. The pressure applied to the upper panel 200 makes aportion of the upper panel 200 move toward the lower panel 100, and theportion of the sensor electrode 252 on the second sensor spacer 242comes in contact with the second sensor pad 183. The pressure is,however, not sufficient to bring the portion of the sensor electrode 252on the first spacer 241 into contact with the first sensor pad 182 andthe first sensor pad 182 is not connected to the second sensor pad 183by the sensor electrode 252. Here, since the sensor electrode 252 is afloating electrode and since the first sensor spacer 241 and the firstsensor pad 182 are separated from each other, a connection between afirst sensor line 123 and a second sensor line 166 is not made and thecoordinates of the pixel are not read.

FIG. 3C illustrates a state in which a force exceeding a referencepressure is applied to the display panel 1 when the second sensor spacer242 is in contact with the second sensor pad 183. If a force of, forexample, 80 gf or greater, is applied to the display panel 1, the firstsensor spacer 241 and the first sensor pad 182 contact each other.Accordingly, the sensor electrode 252 electrically connects the firstsensor pad 182 to the second sensor pad 183.

Since the sensor electrode 252 allows the first sensor pad 182 and thesecond sensor pad 183 to be electrically connected to each other, areference voltage applied to the first sensor pad 182 via the firstsensor line 123 is transmitted through the second sensor pad 183 and isdetectable on the second sensor line 166. Thus the X-coordinate valuecorresponding to a location to which the pressure is applied isrecognized, and the Y-coordinate value corresponding to the location towhich the pressure is applied is read.

In the alternative case, in which the sensor electrode is not a floatingelectrode, but is an integral part of the common electrode or iselectrically connected to the common electrode, the operation of readingthe coordinates of a pixel in an area where pressure is applied isdifferent from the floating sensor electrode case. When a common voltageis present on the common electrode 251 and on the sensor electrode 252,and when the second sensor pad 183 comes in contact with the sensorelectrode 252 the common voltage appears on the second sensor line 166,thus providing the Y coordinate, regardless of the condition of thefirst sensor pad 182. When the pressure is sufficient to bring thesecond sensor pad 183 and the first sensor pad 182 into contact with thesensor electrode 252, the common voltage appears on both the secondsensor line 166 and the first sensor line 123, thus providing the X andY coordinates of the pixel.

Hereinafter, the operating process of the display panel 1, in which adefect is present which causes one of the first sensor pad 182 and thesecond sensor pad 183 to be in contact with the sensor electrode 252 dueto a processing deviation, will be described with reference to FIGS. 4Aand 4B. FIGS. 4A and 4B are cross-sectional views schematically showingthe operating process of a display panel in which despite the absence ofany pressure applied by touch, one of the two sensor pads is in contactwith the sensor electrode.

Referring to FIG. 4A illustrating an initial state in which the displaypanel 1 in which a manufacturing defect is present in that the secondsensor spacer 242 is in contact the second sensor pad 183, where noexternal pressure is applied, and the lower panel 100 and the upperpanel 200 of the display panel 1 are parallel with each other. One ormore or even all of the pixels on the display panel may contain such apressure sensor defect. A height difference between the first sensorspacer 241 and the second sensor spacer 242 may be generated due to aprocessing deviation. However, since the first sensor spacer 241 and thesecond sensor spacer 242 are formed by the same process, the heightdifference between the first sensor spacer 241 and the second sensorspacer 242 can be maintained to be constant. Therefore, if heights ofthe first sensor spacer 241 and the second sensor spacer 242 are greaterthan reference height levels or a cell gap between the upper panel 200and a lower panel 100 is smaller than a reference cell gap, the secondsensor spacer 242 and the second sensor pad 183 contact each other asshown in FIG. 4A, so that the sensor electrode 252 and the second sensorpad 183 are electrically connected to each other.

As described above, if the sensor electrode 252 and the second sensorpad 183 are electrically connected to each other in the initial statewhere there is no external pressure applied, the first sensor pad 182and the sensor electrode 252 are not electrically connected to eachother, the X,Y coordinates of the defective pixel are not read. Thus, itis properly determined that no pressure is applied to the pixel in whichthe defective pressure sensor is present.

Referring to FIG. 4B illustrating a state in which an external forceexceeding a reference pressure is applied to the display panel 1, if apressure, e.g., a force of 80 gf or greater, is additionally applied ina state in which the second sensor spacer 242 is in a contact with thesecond sensor pad 183, the first sensor spacer 241 and the first sensorpad 182 contact each other, so that the sensor electrode 252 allows thefirst sensor pad 182 and the second sensor pad 183 to be electricallyconnected to each other.

As the sensor electrode 252 allows the first sensor pad 182 and thesecond sensor pad 183 to be electrically connected to each other, thereference voltage applied to either the first sensor pad 182 via thefirst sensor line 123 or the second sensor pad 183 via the second sensorline 166 is detectable either at the second sensor line 166 or the firstsensor line, respectively, so that an X-coordinate value indicating thecontacted position when the pressure is applied can be read, and aY-coordinate value indicating the contacted position when the pressureis applied can be read.

In the present invention, a height difference that is intentionallycreated between the first sensor spacer 241 and the second sensor spacer242 in the above-described manner, provides a display panel 1 havingincreased reliability in determining touch location despite the presenceof defects in which either the first sensor spacer 241 or the secondsensor spacer 242 contacts the first or second sensor pad 182 or 183,respectively, due to a processing deviation.

Hereinafter, the manufacturing process of an upper panel of the displaypanel according to the first embodiment of the present invention will bedescribed with reference to FIGS. 5A through 5D. FIGS. 5A through 5D arecross-sectional views showing the manufacturing process of an upperpanel of the display panel shown in FIG. 1.

Referring first to FIG. 5A, the black matrix 220 is formed on the secondsubstrate 210. The black matrix 220 is formed by coating an opaqueorganic material or an opaque metal on the second substrate 210 andpatterning the same by photolithography in which unwanted material isremoved by etching. The black matrix 220 is formed to have apredetermined width to prevent opaque metal patterns from being viewedfrom the lower panel 100. Here, the second substrate 210 may be formedof a transparent insulating material, such as plastic or glass, capableof forming a smoothly curved surface even when a pressure, applied byfor example a finger or a stylus, is applied to the surface of thesecond substrate 210.

Referring to FIG. 5B, the color filter 230 is formed on the secondsubstrate 210 having the black matrix 220. The color filter 230 may beformed by photolithography. The color filter 230 filters white light toprovide one of three primary colors, for example, red, blue and green.The pixels may be arranged in groups of three, wherein the color filtersare arranged in an order of red, green, and blue colors, the order beingrepeated thought the display panel.

Referring to FIG. 5C, the first sensor spacer 241 and the second sensorspacer 242 are formed on the black matrix 220. The first sensor spacer241 and the second sensor spacer 242 may be formed of an organicmaterial or conductive polymer.

The first sensor spacer 241 and the second sensor spacer 242 may beformed by coating a photosensitive organic material on the entiresurface of the second substrate 210 and partially etching the resultantstructure using a slit mask or a halftone mask. That is to say, thefirst sensor spacer 241 and the second sensor spacer 242 may bepartially exposed to generate a height difference therebetween. Usingthe photosensitive organic material as described in the presentembodiment illustrated in FIG. 5C is provided for illustration only.However, in alternative embodiments, inkjet printing may be employed, ora photoresist may be coated on an organic material coating to then bepatterned.

Referring to FIG. 5D, the common electrode 251 is formed on the blackmatrix 220 and the color filter 230, and the sensor electrode 252 isformed on the first sensor spacer 241 and the second sensor spacer 242.

First, a transparent conductive material is applied to the surface ofthe black matrix 220, the color filter 230, the first sensor spacer 241and the second sensor spacer 242 by sputtering or the like. To this end,ITO or IZO is sued as the transparent conductive material. Thetransparent conductive material layer is patterned by photolithographyin which a step of etching using a mask is used to form the commonelectrode 251 and the sensor electrode 252.

Hereinafter, a display panel according to a second embodiment of thepresent invention will be described with reference to FIG. 6. FIG. 6 isa cross-sectional view of a display panel according to a secondembodiment of the present invention. For descriptive convenience,components having the same function as described with reference to thefirst embodiment are respectively identified by the same referencenumerals, and their repetitive description will be omitted.

In the display panel 1′ according to the second embodiment of thepresent invention, lateral sides of a first sensor spacer 241′ and asecond sensor spacer 242′ are connected to each other. In detail, anupper panel 200 includes a second substrate 210 upon which are disposeda black matrix 220 for blocking light leakage, a color filter 230 fordisplaying colors, and a common electrode 251 for applying a commonvoltage to the liquid crystal layer 300.

The black matrix 220 is formed on the second substrate 210. The blackmatrix 220 is formed to overlap the TFT of a lower panel 100, and otherparts of the lower panel including, a gate line 121, a data line 162, afirst sensor wiring 123 and a second sensor wiring 166. A color filter230 is formed on the second substrate in an opening in the black matrix220 corresponding to a pixel area.

The common electrode 251 is formed on the color filter 230 and the blackmatrix 220.

The first sensor spacer 241′ and the second sensor spacer 242′ may beformed on the black matrix 220. That is to say, the first sensor spacer241′ and the second sensor spacer 242′ are formed to overlap the blackmatrix 220 by which light is blocked. A sensor electrode 252 is formedon the first sensor spacer 241′ and the second sensor spacer 242′. Thefirst sensor spacer 241′ and the second sensor spacer 242′ have therespective lateral sides connected to each other by a portion of thematerial of the sensor spacers which remains on the black matrix betweenthe first sensor spacer and the second sensor spacer. In other words,two peaks may be formed on a single island thus providing the firstsensor spacer 241′ and the second sensor spacer 242′. Here, the firstsensor spacer 241′ and the second sensor spacer 242′ may be shaped inthe form of a peak.

The first sensor spacer 241′ and the second sensor spacer 242′ protrudetoward the first substrate 110. The second sensor spacer 242′ protrudestoward the first substrate 110 farther than the first sensor spacer 241′does.

A height difference between the first sensor spacer 241′ and the secondsensor spacer 242′ may be 0.1 μm or greater. If the height differencebetween the first sensor spacer 241′ and the second sensor spacer 242′is maintained to be 0.1 μm or greater, a difference between the distancebetween the first sensor pad 182 and the first sensor spacer 241′ andthe distance between the second sensor pad 183 and the second sensorspacer 242′ can be made to be 0.1 μm or greater.

Also, the sensor electrode 252 formed on the first sensor spacer 241′and the second sensor spacer 242′ may be formed of the same materialthat is used in forming the common electrode 251 by the same process.Further, the sensor electrode 252 may be insulated from the commonelectrode 251 so as to be at a floating potential. The sensor electrode252 may be formed on the first sensor spacer 241′ and the second sensorspacer 242′ in the shape of an island.

Hereinafter, a display panel according to a third embodiment of thepresent invention will be described with reference to FIG. 7. FIG. 7 isa cross-sectional view of a display panel according to a thirdembodiment of the present invention. For descriptive convenience,components having the same function as described with reference to thefirst embodiment are respectively identified by the same referencenumerals, and their repetitive description will be omitted.

The display panel 1″ according to the third embodiment of the presentinvention includes a first sensor spacer 171 and a second sensor spacer172, both formed on a lower panel 100.

The first sensor spacer 171 and second sensor spacer 172 are formed on afirst substrate 110. The first sensor spacer 171 and the second sensorspacer 172 are formed to overlap a black matrix 220 by which light isblocked, and a first sensor pad 182′ and a second sensor pad 183′ areformed on the first sensor spacer 171 and the second sensor spacer 172,respectively. The first sensor spacer 171 and the second sensor spacer172 may be formed of an organic material.

The first sensor spacer 171 and the second sensor spacer 172 protrudetoward a second substrate 210. The first sensor spacer 171 protrudestoward the second substrate 210 farther than the second sensor spacer172 does. The first sensor spacer 171 and the second sensor spacer 172may be formed to be adjacent to each other or to be spaced apart fromeach other.

A common electrode 251 overlapping the first sensor spacer 171 and thesecond sensor spacer 172 may be formed on a second substrate 210. Inthis embodiment, a portion of the common electrode 251 overlapping thefirst sensor spacer 171 and the second sensor spacer 172 becomes asensor electrode.

When a pressure is applied to a location on an upper panel 200 accordingto a user's contact, the common electrode 251 as well as the secondsubstrate 210 become curved downward, and the common electrode 251 comesinto contact with the first sensor pad 182′ and the second sensor pad183′ formed on the first sensor spacer 171 and the second sensor spacer172, so that the location on the upper panel 200 to which the pressureis applied can be ascertained.

Before an external force is applied to the upper panel 200, the firstsensor spacer 171 and the second sensor spacer 172 are spaced apart fromthe common electrode 251 by predetermined distances. Here, the distancebetween the common electrode 251 and the first sensor spacer 171 may besmaller than the distance between the common electrode 251 and thesecond sensor spacer 172. Thus, if the external force is applied to theupper panel 200, the first sensor spacer 171 comes into contact with thecommon electrode 251. Then, if the external force exceeds a referencepressure supported by the first sensor spacer 171 is applied to theupper panel 200, the first sensor spacer 171 may be compressed and thesecond sensor spacer 172 comes into contact with the common electrode251. As described above, when the first sensor pad 182′ and the secondsensor pad 183′ come into contact with the common electrode 251, acommon voltage applied to the common electrode 251 is transmitted to thefirst sensor pad 182′ and from there to the first sensor line 123, andto the second sensor pad 183′ and from there to the second sensor line166, so that the contacted positions to which the pressure is appliedcan be recognized.

However, the sensor electrode 252 is not necessarily a part of thecommon electrode 251. That is to say, the sensor electrode 252 may be afloating electrode that is separated from the common electrode 251. Forexample, the sensor electrode may be formed by patterning a part of thecommon electrode 251. Here, the sensor electrode may be formed such thatit overlaps both the first sensor spacer 171 and the second sensorspacer 172.

A height difference between the first sensor spacer 171 and the secondsensor spacer 172 may be 0.1 μm or greater. If the height differencebetween the first sensor spacer 171 and the second sensor spacer 172 ismaintained to be 0.1 μm or greater, a difference between a distancebetween the common electrode 251 and the first sensor spacer 171, and adistance between the common electrode 251 and the second sensor spacer172, can be made to be 0.1 μm or greater.

While the present invention has been particularly shown and describedwith reference to exemplary embodiments thereof, it will be understoodby those of ordinary skill in the art that various changes in form anddetails may be made therein without departing from the spirit and scopeof the present invention as defined by the following claims. It istherefore desired that the present embodiments be considered in allrespects as illustrative and not restrictive, reference being made tothe appended claims rather than the foregoing description to indicatethe scope of the invention.

What is claimed is:
 1. A display panel comprising: a first substrate; asecond substrate that is disposed to face the first substrate; a commonelectrode that is formed on the second substrate; a first sensor spacerthat is formed on the first substrate and protrudes toward the secondsubstrate; a second sensor spacer that is formed on the first substrateand protrudes toward the second substrate; a first sensor pad that isformed on the first sensor spacer; a second sensor pad that is formed onthe second sensor spacer and is spaced apart from the first sensor pad;and a sensor electrode that is formed on the second substrate to overlapthe first sensor pad and the second sensor pad, wherein the secondsensor spacer protrudes toward the second substrate farther than thefirst sensor spacer.
 2. The display panel of claim 1, wherein a distancebetween the second sensor pad and the sensor electrode is smaller than adistance between the first sensor pad and the sensor electrode.
 3. Thedisplay panel of claim 2, wherein a difference between the distancebetween the second sensor pad and the sensor electrode and the distancebetween the first sensor pad and the sensor electrode is 0.1 μm orgreater.
 4. The display panel of claim 2, wherein the sensor electrodeand the second sensor spacer contact each other with the second sensorpad disposed therebetween.